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CVE-2026-64379 (GCVE-0-2026-64379)

Vulnerability from cvelistv5 – Published: 2026-07-25 08:50 – Updated: 2026-08-17 04:54
VLAI
Title
smb: client: mask server-provided mode to 07777 in modefromsid
Summary
In the Linux kernel, the following vulnerability has been resolved: smb: client: mask server-provided mode to 07777 in modefromsid When modefromsid is active, parse_dacl() applies the server-provided sub_auth[2] value from the NFS mode SID to cf_mode without masking to 07777. Apply the correct masking, same as in the read path.
Severity
7.1 (High)
CVSS:3.1/AV:N/AC:L/PR:N/UI:R/S:U/C:N/I:L/A:H
Assigner
References
Impacted products
Vendor Product Version CPE status
Linux Linux Affected: e2f8fbfb8d09c06decde162090fac3ee220aa280 , < 5f6f2241034f189c69d4d0b5f8fe24a0c25b0c14 (git)
Affected: e2f8fbfb8d09c06decde162090fac3ee220aa280 , < ee2216dbdf0c677e89bb43e03247dba590ed00ef (git)
Affected: e2f8fbfb8d09c06decde162090fac3ee220aa280 , < f511807feee7cb29b61bdfa86472c7e9e2e5df94 (git)
Affected: e2f8fbfb8d09c06decde162090fac3ee220aa280 , < 08c600b7e1818539ba5efee4cdb06215c245ca78 (git)
Affected: e2f8fbfb8d09c06decde162090fac3ee220aa280 , < b84e002e0df26bbc6cbd3ca01b8212601fe0ae7d (git)
Affected: e2f8fbfb8d09c06decde162090fac3ee220aa280 , < c6c484a7d5bff6b929a86d7ed5130f29834c6a0d (git)
Affected: e2f8fbfb8d09c06decde162090fac3ee220aa280 , < f80add1bfb3425100a325b14f19648e75669a954 (git)
Affected: e2f8fbfb8d09c06decde162090fac3ee220aa280 , < e3d9c7160d483fc8f9e225aafad8ecbbc43f3151 (git)
guessed Create a notification for this product.
Linux Linux Affected: 5.4
Unaffected: 0 , < 5.4 (semver)
Unaffected: 5.10.261 , ≤ 5.10.* (semver)
Unaffected: 5.15.212 , ≤ 5.15.* (semver)
Unaffected: 6.1.178 , ≤ 6.1.* (semver)
Unaffected: 6.6.145 , ≤ 6.6.* (semver)
Unaffected: 6.12.96 , ≤ 6.12.* (semver)
Unaffected: 6.18.39 , ≤ 6.18.* (semver)
Unaffected: 7.1.4 , ≤ 7.1.* (semver)
Unaffected: 7.2 , ≤ * (original_commit_for_fix)
guessed Create a notification for this product.
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              "versionType": "original_commit_for_fix"
            }
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      "cpeApplicability": [
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          "nodes": [
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                  "criteria": "cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*",
                  "versionEndExcluding": "5.10.261",
                  "versionStartIncluding": "5.4",
                  "vulnerable": true
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                  "versionEndExcluding": "5.15.212",
                  "versionStartIncluding": "5.4",
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                  "versionStartIncluding": "5.4",
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              "negate": false,
              "operator": "OR"
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      ],
      "descriptions": [
        {
          "lang": "en",
          "value": "In the Linux kernel, the following vulnerability has been resolved:\n\nsmb: client: mask server-provided mode to 07777 in modefromsid\n\nWhen modefromsid is active, parse_dacl() applies the server-provided\nsub_auth[2] value from the NFS mode SID to cf_mode without masking to\n07777. Apply the correct masking, same as in the read path."
        }
      ],
      "metrics": [
        {
          "cvssV3_1": {
            "baseScore": 7.1,
            "baseSeverity": "HIGH",
            "vectorString": "CVSS:3.1/AV:N/AC:L/PR:N/UI:R/S:U/C:N/I:L/A:H",
            "version": "3.1"
          },
          "scenarios": [
            {
              "lang": "en",
              "value": "AV:N - A malicious or compromised SMB server can supply the crafted NFS mode SID through a network-delivered QUERY_INFO security descriptor.\nAC:L - With modefromsid enabled, the server directly controls sub_auth[2], and the invalid inode-type bits are applied deterministically without a race or memory-layout dependency.\nPR:N - The attacker acting as the SMB server needs no privileges on the client; client authentication to the share is a victim-side condition rather than an attacker privilege.\nUI:R - A victim administrator or service must mount the SMB share with modefromsid, or subsequently access a crafted object on an existing mount.\nS:U - The corrupted mode and resulting VFS behavior remain within the Linux kernel\u0027s existing security authority and do not cross a VM, IOMMU, or sandbox boundary.\nC:N - The flaw only injects bits into the 16-bit mode field and provides no out-of-bounds read, memory disclosure, or direct mechanism for returning client data to the attacker.\nI:L - The attacker can alter S_IFMT bits in cf_mode and thereby change the inode\u0027s perceived type and selected VFS operations, but this is a constrained metadata modification rather than an arbitrary write or control-flow primitive.\nA:H - Forging the root or widespread inode types can prevent the share from mounting or render its objects unusable; for CIFS-root or critical SMB-backed deployments this can cause complete service availability loss."
            }
          ]
        }
      ],
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        "dateUpdated": "2026-08-17T04:54:30.613Z",
        "orgId": "416baaa9-dc9f-4396-8d5f-8c081fb06d67",
        "shortName": "Linux"
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        },
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        {
          "url": "https://git.kernel.org/stable/c/e3d9c7160d483fc8f9e225aafad8ecbbc43f3151"
        }
      ],
      "title": "smb: client: mask server-provided mode to 07777 in modefromsid",
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    "assignerShortName": "Linux",
    "cveId": "CVE-2026-64379",
    "datePublished": "2026-07-25T08:50:29.717Z",
    "dateReserved": "2026-07-19T15:36:31.784Z",
    "dateUpdated": "2026-08-17T04:54:30.613Z",
    "state": "PUBLISHED"
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      "date": "2026-09-05",
      "epss": "0.00309",
      "percentile": "0.23277"
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      "cve": "CVE-2026-64379",
      "id": "msrc_CVE-2026-64379",
      "initial_release_date": "2026-07-26T01:01:48.000Z",
      "product_status:known_affected": "1",
      "source": "Microsoft CSAF VEX",
      "status": "final",
      "title": "smb: client: mask server-provided mode to 07777 in modefromsid",
      "url": "https://msrc.microsoft.com/csaf/vex/2026/msrc_cve-2026-64379.json",
      "version": "2"
    },
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    "redhat_vex": {
      "aggregate_severity": "Moderate",
      "current_release_date": "2026-08-20T08:12:17+00:00",
      "cve": "CVE-2026-64379",
      "id": "CVE-2026-64379",
      "initial_release_date": "2026-07-25T00:00:00+00:00",
      "product_status:fixed": "762",
      "product_status:known_affected": "22",
      "product_status:known_not_affected": "42",
      "source": "Red Hat CSAF VEX",
      "status": "final",
      "title": "kernel: smb: client: mask server-provided mode to 07777 in modefromsid",
      "url": "https://security.access.redhat.com/data/csaf/v2/vex/2026/cve-2026-64379.json",
      "version": "3"
    },
    "suse_vex": {
      "aggregate_severity": "moderate",
      "current_release_date": "2026-08-22T00:55:19Z",
      "cve": "CVE-2026-64379",
      "id": "CVE-2026-64379",
      "initial_release_date": "2026-07-25T16:00:34Z",
      "product_status:known_affected": "292",
      "product_status:known_not_affected": "6",
      "product_status:recommended": "65",
      "source": "SUSE CSAF VEX",
      "status": "interim",
      "title": "SUSE CVE CVE-2026-64379",
      "url": "https://ftp.suse.com/pub/projects/security/csaf-vex/cve-2026-64379.json",
      "version": "6"
    }
  }
}



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Forecast uses a logistic model when the trend is rising, or an exponential decay model when the trend is falling. Fitted via linearized least squares.

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  • Confirmed: The vulnerability has been validated from an analyst's perspective.
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  • Not patched: The vulnerability was not observed as successfully patched by the user who reported the sighting.


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